The invention concerns a reeling drum for a paper or board machine or equivalent, onto which reeling drum a material web, in particular paper or board, is reeled. Axle journals are fixed to the ends of the reeling drum by means of end joints. By means of the axle journals, the reeling drum is supported in a revolving manner on the machine frame by means of bearing means.
The paper produced in a paper machine is wound around a reeling drum in a reel-up to make a jumbo roll. The most common type of reel-up in use is a reel-up driven from the circumference, wherein the reeling drum revolves against a reeling cylinder. With the present day reeling drums provided with rubber coating or polyurethane coating, the control of the linear load is indefinite at the bottom of the roll.
In the present reeling drums, the hardness of the roll face and the properties of compressibility are quite decisively different from the corresponding properties of paper. As a consequence, when the reeling is started on an empty reeling drum, the desired distribution of hardness and density of the reeled paper is not attained.
It is a further significant problem, in particular in the case of LWC- and SC-papers, that such papers form very dense rolls on the reeling drum, which rolls are also rigid. The reeling drum is, however, deflected because of the load, and, since the rigid paper roll present on the reeling drum cannot deflect to a corresponding extent, the pressure produced by the paper roll on the reeling drum is considerably higher at the edges of the reeling drum than in its middle area. These drawbacks produce web breaks and roll-bottom broke in the reeling, and the amount of broke in one roll may be of an order of up to 2000 meters. Thus, in a paper mill, the annual losses incurred because of broke amount even to dozens of millions of FIM.
In the prior art, attempts have been made to eliminate the problems arising from deflection of the reeling drum and from the resulting unfavorable distribution of pressure so that the diameter of the reeling drum has been made larger. In this way, of course, the effect has been achieved that the deflection of the reeling drum has been reduced, whereby the differences in the pressure distribution on the reeling drum are lower accordingly.
However, it is a major drawback of this solution that it is not been possible to reel an equally large amount of paper onto a reeling drum with a large diameter as done previously. Thus, this solution also causes losses for the paper mills because of smaller paper rolls.